This project represents a multidisciplinary study of auditory processing problems in the elderly, involving neuropsychology, neurology, audiology, and otolaryngology. The specific aim is to determine whether the auditory processing problems of the elderly are primarily a manifestation of 1) an auditory-specific disorder, 2) a broader cognitive disorder, or 3) a complex disorder involving interactive senescent changes in both the auditory and cognitive domains. Our focus is twofold: to investigate 1) how senescent cognitive and adaptive disorders may affect the behavioral manifestations of age-dependent auditory complaints due to presbyacusis, and 2) how degree of disorder may be related to cognitive and adaptive behaviors of the elderly. Our hypothesis is that the auditory behavioral changes in the elderly are a multidimensional phenomenon that cannot be understood solely on the basis of physiologic changes within the auditory system. We propose that a meaningful study of presbyacusis requires a multivariate approach in which consideration is given not only to auditory processes per se, but also to the cognitive processes that mediate behavior. Experimental subjects will be 225 individuals between 60-90 years of age with auditory dysfunction due to presbyacusis. Control subjects will be 150 individuals divided into two groups controlling for the effects of age (75 elderly persons with no auditory disorder) and hearing loss (75 young persons with hearing loss). All subjects will complete a battery of standard and experimental auditory and neuropsychological tests, e.g., pure tone and speech audiometry, auditory evoked potentials, intelligence scale, memory function, reaction time, etc. Data will be analyzed by multiple regression technique. A multivariate approach seems to be uniquely appropriate for the study of the perceptual consequences of presbyacusis. The intersubject variability that has confounded interpretation of many previous single factor studies may actually be advantageous in a multivariate approach. Large intersubject differences should theoretically enhance our ability to detect statistical correlations between measures. The significance of this project is that results may provide a more differentiated view of presbyacusis. We may be able to define the precise ways in which cognitive factors are linked to specific variations in the auditory processing abilities of the elderly. Understanding the relation between auditory and cognitive factors may provide important information for rehabilitation and hearing aid prescription.